Static magnetic field-enhanced osteogenic differentiation of human umbilical cord-derived mesenchymal stem cells via matrix vesicle secretion.

METHODS: In methodology, WJMSCs were treated with a 0.4-T SMF. The cell viability was tested using the MTT assay. For the osteogenic analysis, the alkaline phosphatase activity assay and alizarin red S staining were performed. The osteogenic-related gene expression of ALP, BMP-2, and Runx2 was examined using real-time polymerase chain reaction. Scanning electron microscopy combined with energy-dispersive X-ray spectroscopy was used to analyze matrix vesicle secretion. RESULTS: The cell viability showed no significant difference between the SMF-treated group and the sham-exposed cells. However, the SMF-treated group exhibited significantly more mineralized nodule formation and higher ALP activity than their control counterparts (p < .05). The expressions of osteogenic-related markers, ALP, BMP-2, and Runx2, were also significantly higher in the SMF-treated WJMSCs. The scanning electron microscopy results showed much more matrix vesicle secretion in the SMF-treated cells than in the sham-treated cells. A mineralized sheath was noted in the SMF-treated cells, along with a sporadic accumulation of spherical mineralized deposits on the cell surface. CONCLUSIONS: The results suggest that 0.4-T SMF treatment enhances the osteogenesis of WJMSCs at the early-to-middle stage of osteogenic differentiation by increasing the matrix vesicle secretion and mineralization.

Cellular response of calcium phosphate bone substitute containing hydroxyapatite and tricalcium phosphate.

PURPOSE: This study developed calcium phosphate bone substitutes and their microstucture and in vitro cell response were evaluated in comparison with commercial hydroxyapatite (HA). MATERIALS: HA powder was ball-milled and then sintered to transfer into the calcium phosphate bulks (CPB). The density, hardness, and microstructure of the CPB were investigated. The viability and proliferation of MG63 osteoblast-like cells on the commercial HA and the CPB were evaluated. RESULTS: The x-ray diffraction confirmed that the CPB consisted of α-tricalcium phosphate (α-TCP), CaO, and HA. The hardness, density, and α-TCP-to-HA ratio of the CPB decreased when increasing the sintering duration. Cell tests demonstrated that the CPB exhibited an earlier cell-spread response than the commercial HA. CONCLUSIONS: This study demonstrated that a phase transformation of HA into α-TCP and CaO was achieved by sintering. The cell tests indicated that the CPB has favorable in vitro cellular performance, which implied that it presented potential as bone substitute.